(1) Field of the Invention
The present invention relates to a method for treating an of organohalogen compound, particularly, to a preferred method for treating the organohalogen compound by destroying the organohalogen compound with a catalyst.
(2) Description of the Prior Art
Organohalogen compounds contaminate air, rivers, water underground, soil, etc. Particularly, the organohalogen compounds having toxicity such as a cancer-causing property are regarded as problems in view of environmental pollution. Release suppression technology of the organohalogen compound, and destruction-treatment technology of the organohalogen compound existing in the environment as contaminants after releasing are now under development. The above destruction-treatment technology is aimed at destructing the organohalogen compound in released waste or in the environment after releasing. Therefore, an object of the destruction-treatment is the organohalogen compound of relatively low concentration. Currently, there are some organohalogen compounds which are regarded as a source material of ozone layer destruction, or a source material of green effect, even if it may be less toxic.
Therefore, release suppression technology and recovery-treatment technology for such organohalogen compounds are now under development. In the recovery-treatment technology, a large amount of recovered organohalogen compound is treated for destruction. Therefore, in view of economical aspect of the facility, it is necessary to destruct the organohalogen compound of relatively high concentration, and to make it harmless.
As for a treating method to make the organohalogen compound harmless, there are various methods which are well known. Among the various methods, a method for destruction by combustion, a method for destruction using plasma, and a method for destruction by cracking using high temperature steam have a large defect such as a large energy consumption. A method for destruction by ultraviolet ray, a method for destruction by irradiation, and a method for destruction using a micro-organism have a small destruction efficiency and a small destructing velocity. A method for destruction of an organohalogen compound using combustion has a problem to generate strong poisonous substance such as dioxin. On the contrary, a method for destructing the organohalogen compound using a catalyst receives an attention as a most effective method, because the method scarcely has the above described defects.
As for the method for treating organohalogen compounds using a catalyst, various methods have been disclosed hitherto, for example, as follows; JP-A-52-114468 (1977) disclosed a treating method using a catalytic destruction apparatus of air including an organohalogen compound. JP-A-3-42015 (1991) disclosed a method for destructing recovered flons. JP-A-3-66388 (1991) disclosed a treating method of flon of high concentration such as 6 mole %.
Destructing objects of the treating method disclosed in JP-A-52-114468 (1977) are organohalogen compounds of extremely low concentration. Therefore, it is difficult to destruct recovered organohalogen compounds, of which treatment has currently been becoming necessary, with a high efficiency under a high concentration. The treating method disclosed in JP-A-52-114468 (1977) does not teach any countermeasure against corrosion products, which are generated with heating the organohalogen compound, because concentrations of corrosive materials (chlorine, hydrogen chloride, fluorine, hydrogen fluoride etc.) generated at the destruction of the organohalogen compound are low. Furthermore, the treating method taught only insufficient countermeasure against corrosive materials generated with destructing the organohalogen compound. The method disclosed in JP-A-3-42015 (1991) is a method treating organohalogen compound of low concentrations such as 5000 ppm, and therefore, no countermeasure for the corrosive materials generated at heating and destructing the organohalogen compound was taught, which is the same in JP-A-52-114468 (1977).
The treating method disclosed in JP-A-3-66388 (1991) did not teach any practical means for supplying flon of a high concentration, nor any countermeasure against corrosive materials generated by heating the organohalogen compound. Furthermore, no practical countermeasure against corrosive materials generated at destructing flon was taught except neutralization with an alkali.
One of a few defects of the destruction method for an organohalogen compound using a catalyst is a smaller destructing efficiency than destructing efficiencies of the destructing method by combustion and the destructing method by plasma. The destructing efficiencies of the organohalogen compound by the destructing method by combustion and the destructing method by plasma is approximately in a range of 99.999xcx9c99.9999%. On the contrary, the destructing efficiencies of the organohalogen compound by the destructing method using a catalyst is approximately in a range of 99.9xcx9c99.99%. The above destructing efficiencies of the destructing method using a catalyst scarcely make a problem in practical use. However, when the method is applied to a material such as flon, to which the United Nation Environmental Plan gives a guideline for the destructing efficiency as at least 99.99%, it is necessary to add an extra means in order to comply with the guideline. For example, JP-A-6-106172 discloses a method, in which undestructed organohalogen compound in exhaust gas from the catalytic destruction process are eliminated from the exhaust gas by being adsorbed into an adsorbent. The undestructed organohalogen compounds adsorbed in the adsorbent are released and treated again with the catalyst. However, in accordance with the above method, the main catalytic destruction process must be stopped when the released undestructed organohalogen compounds from the adsorbent are treated, and accordingly, the operation efficiency of the catalytic destruction facility is decreased.
As explained above, conventional methods for treating the organohalogen compounds have difficulty in operating the facility for destructing the organohalogen compound of a high concentration with a high destructing efficiency, a high operating efficiency of the facility, and appropriate countermeasures against corrosive materials generated by the destruction.
The object of the present invention is to provide a method for treating an organohalogen compound, which is capable of suppressing generation of corrosive material and destructing the organohalogen compound effectively, and an apparatus therefor.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of suppressing generation of corrosive material further, and an apparatus therefor.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of controlling supplying the amount of the organohalogen compound easily.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of simplifying the water supplying facility.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of simplifying the water supplying facility.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of protecting corrosion at the upstream region of the catalytic layer.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of suppressing corrosion caused by the destruction gas, which is generated by catalytic destruction of the organohalogen compound, and an apparatus therefor.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of preventing the exhaust gas released from the catalytic layer from generating poisonous substance.
Another object of the present invention is to provide a method for treating an organohalogen compound, which is capable of improving the corrosive environment caused by the exhaust gas released from the catalytic layer.
Another object of the present invention is to provide an apparatus for treating an organohalogen compound, which is capable of suppressing corrosion of the structural material of the catalytic layer.
Another object of the present invention is to provide an apparatus for treating an organohalogen compound, which is capable of improving an efficiency of removal for the acidic gas released from the catalytic layer.
The feature of a first aspect of the invention for of achieving the objects of the present invention is in the steps of heating a carrier gas by a heater, adding organohalogen compound to the carrier gas passed through the heater, and supplying a carrier gas containing organohalogen compound to a catalytic layer.
The feature of a second aspect of the invention for achieving the objects of the present invention is in adding the organohalogen compound to the carrier gas which has been mixed with steam.
The feature of a third aspect of the invention for achieving the objects of the present invention is in adding the organohalogen compound in a liquid condition, which is in a liquid state at room temperature, to the carrier gas.
The feature of a fourth aspect of the invention for by achieving the objects of the present invention is in adding the organohalogen compound in a liquid state under a pressurized condition, which has a boiling point near the room temperature, to the carrier gas.
The feature of a fifth aspect of the invention for achieving the objects of the present invention is in the steps of burning hydrogen or hydrocarbon fuel in the heater, adding the organohalogen compound to the combustion gas released from the heater, and supplying the combustion gas containing the organohalogen compound to the carrier gas.
The feature of a sixth aspect of the invention for achieving the objects of the present invention is in controlling the heating temperature at the heater so that the temperature of the gas released from the heater is in a range from a temperature where at the organohalogen compound destructs with catalyst to a temperature where at the organohalogen compound itself starts to destruct at least partly.
The feature of a seventh aspect of the invention for achieving the objects of the present invention is in cooling the exhaust gas soon after release from the catalytic layer.
The feature of an eighth aspect of the invention for achieving the objects of the present invention is in that the organohalogen compound is a gas containing chlorine, and the exhaust gas released from the catalytic layer is cooled soon after the releasing.
The feature of a ninth aspect of the invention for achieving the objects of the present invention is in adding a reactive material, which reacts with the acidic gas contained in the exhaust gas which is released from the catalytic layer, to the exhaust gas released from the catalytic layer.
The feature of a tenth aspect of the invention for achieving the objects of the present invention is in providing a means for preventing the entry of mist, which is generated with liquid spray by a spraying means, into the catalytic layer in a space which is formed in a catalyst container at downstream region of the catalytic layer.
The feature of an eleventh aspect of the invention for achieving the objects of the present invention is in providing a means for preventing the transfer of mist, which is generated with liquid spray by the spraying means, to the downstream region of the catalytic layer at the space.
The above first and second aspects of the inventions can prevent the organohalogen compound from generating corrosive substance with heating by the carrier gas, and destruction of the organohalogen compound can be performed with a preferable efficiency, because the organohalogen compound is added to the carrier gas which is previously heated by the heater and released from the heater. In order to destruct the organohalogen compound effectively with catalyst, it is necessary to elevate the temperature of the organohalogen compound higher than the reaction temperature of the catalyst with the organohalogen compound. However, if the temperature is excessively high, the organohalogen compound destructs to generate corrosive substance. Even if the temperature of the gas released from the heater is within a range in which generation of the corrosive substance is suppressed, the temperature inside the heater reaches locally the temperature at which the corrosive substance is generated. Accordingly, if the organohalogen compound is supplied into the heater, the organohalogen compound is destructed at a local region which is heated to an excessively high temperature to generate the corrosive substance. The carrier gas, which is heated by the heater and released from the heater, has substantially uniform temperature distribution and no local elevation of the temperature. Therefore, if the organohalogen compound is added into the carrier gas at downstream region of the heater, the destruction of the organohalogen compound with the local heating of the carrier gas can be suppressed.
In accordance with the present invention, the organohalogen compound which is the object of the treatment is a compound containing at least one of chlorine, fluorine, and bromine. Practically, the compound is one of an organochloro-compound, organofluoro-compound, and organobromo-compound. As the organochloro-compound, there are methylchloride, chloroform, carbon tetrachloride, ethylene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, hexachloroethane, vinyl chloride, vinylidene chloride, tetrachloroethylene, chlorobenzene, benzyl chloride, benzene hexachloride, ethylene glycol, trichloroethylene, and others. As the organofluoro-compound, there are CFC-11, CFC-12, CFC-13, CFC-14, CFC-15, HCFC-22, HCFC-141, HCFC-225, and others. As the organobromo-compound, there are Halon-1211, Halon-1301, Halon-2402, and others.
The organochloro-compound contains chlorine, and generates mainly corrosive gas (acidic) such as chlorine, hydrogen chloride, and the like by destruction. The organofluoro-compound contains fluorine, and generates mainly corrosive gas (acidic) such as fluorine, hydrogen fluoride, and the like by destruction. The organobromo-compound contains bromine, and generates mainly corrosive gas (acidic) such as bromine, hydrogen bromide, and the like by destruction.
As an example of the carrier gas for the organohalogen compound, air can be used. The carrier gas is used for introducing the organohalogen gas into the catalytic layer. Therefore, the carrier gas has to be inert chemically and thermally, and an inert gas such as nitrogen, argon, and the like can be used other than air. In economical view, air is preferably used as the carrier gas.
Further, as for the heater, any of electric heater and combustor can be used. However, in view of heating efficiency, the combustor is preferably used. As the carrier gas (especially, combustion air) is directly heated with heat generated by combustion of fuel in the combustor, the combustion efficiency is remarkably high. The temperature inside the combustor reaches a high temperature locally by combustion of fuel (when town gas is used for the fuel, the burning temperature reaches locally 1000xc2x0 C.).
Flon-113, one of the organohalogen compounds, starts partly a destructing reaction when the temperature exceeds 700xc2x0 C., and generates strongly corrosive gases such as HF, HCl, and the like. Therefore, the piping and other components for supplying the organohalogen compound to the catalytic layer must be composed of significantly anti-corrosive materials. However, in accordance with the first aspect of the invention, the materials having not so strong anti-corrosion property can be used as the construction material for the piping and other component.
The second aspect of the invention generates the following effect with the effect generated by the first aspect of the invention. The temperature of the carrier gas is lowered, because the heated carrier gas is mixed with steam before mixing the carrier gas and the organohalogen compound. Therefore, a probability to generated the corrosive substance with destruction of the organohalogen compound by heating decreases to lower than that of the first aspect of the invention
The steam is used for supplying hydrogen and oxygen which are necessary for destructing the organohalogen compound with catalyst. For instance, when flon 113 is destructed by hydrolysis, the destruction reaction proceeds as follows;
C2Cl3F3+3H2Oxe2x86x923HCl+3HF+CO2+CO
The amount of the steam necessary for the hydrolysis is 3 moles per 1 mole of flon 113. The amount of the steam is supplied approximately 1.0xcx9c2.0 times of an equivalent amount necessary for the destruction based on the kind and the amount of the organohalogen compound. The supplying amount of the steam is preferably controlled so as to be within the above range. Depending on the kind of the catalyst, the destruction is performed not by hydrolysis but by oxidation. In this case, as hydrogen is not necessary, supply of the steam is not necessary.
The third aspect of the invention facilitates control of the supplying amount of the organohalogen compound, because the organohalogen compound, which is liquid at room temperature, is added in a liquid condition to the carrier gas in addition to the effects generated by the first and second aspects of the inventions. The liquid organohalogen compound can be supplied quantitatively. When the organohalogen compound is in a gaseous condition, the control of the supplying amount becomes complex, because both volume and pressure must be controlled.
The third aspect of the invention is explained practically hereinafter. The organohalogen compound can be mixed in a gaseous condition with the carrier gas and steam. However, if the organohalogen compound is mixed in a liquid condition with the carrier gas and steam, the liquid organohalogen compound can be vaporized by sensible heat of the carrier gas and the steam, and accordingly, a facility for vaporization of the liquid organohalogen compound, which is usually provided separately, can be omitted. Furthermore, some of organohalogen compounds have respective boiling point which is close to room temperature. In this case, stable supply of the organohalogen compound is difficult, because the organohalogen compound is liquefied or vaporized depending on variation of the environmental temperature around the treating apparatus. As one of countermeasures against the above problem, a method for supplying the organohalogen compound in a gas condition or a liquid condition by controlling the temperature can be thought. However, the above method is not desirable, because a large amount of energy is necessary for controlling the temperature, and precise temperature management of the supply piping and other components are required.
The fourth aspect of the invention generates the same effect as the third aspect of the invention, because the organohalogen compound having a boiling point which is close to room temperature is pressurized and added in a liquid condition to the carrier gas. Practically, a stable supply and a stable flow rate measurement are realized by pressurizing inside the treating apparatus and maintaining the inside pressure from the treating apparatus to the outlet valve higher than a saturated pressure at the environmental temperature around the treating apparatus so as to keep this organohalogen compound in a liquid condition. However, the fourth aspect of the invention requires a more complex system than the third aspect of the invention, because an extra pressurizing apparatus is necessary.
The fifth aspect of the invention can decrease the amount of water (including steam) to be added to the carrier gas, i.e. the combustion gas, because hydrogen or hydrocarbon fuel is burnt in the heater, and the organohalogen compound is added to the combustion gas released from the heater. Therefore, a facility for supplying water can be simplified. When a combustor is used as the heater and hydrogen or hydrocarbon fuel is used as the fuel, steam is generated as a combustion product, and the steam can be utilized for the destruction reaction of the organohalogen compound at the catalytic layer. Naturally, the amount of water supplied externally can be decreased. Accordingly, the facility for supplying water can be simplified. As the hydrocarbon fuel, petroleum, petroleum group gas, alcohol fuel, natural gas, hydrogen, and others can be used. Sulfur component in the fuel has a possibility to shorten the life of the catalyst. Therefore, use of hydrocarbon such as petroleum group gas as propane gas, alcohol fuel, hydrogen, and others, which includes no sulfur, is desirable.
Depending on the kind and the treating amount of the organohalogen compound, a total amount of steam necessary for its destructing reaction can be supplied by the steam generated by the combustion of the organohalogen compound.
For instance, when destructing one mole of flon 113, which is one of the organohalogen compounds, only three moles of steam is necessary. If one mole of propane, (C3H8), is used as the fuel which is burnt in the combustor, four moles of steam is generated by the combustion of the propane. Accordingly, it is not necessary to add additional water to the carrier gas supplied to the catalyst layer. The apparatus for treating organohalogen compounds used for the above treatment exclusively does not requires any water supply facility.
In accordance with the sixth aspect of the invention the destruction of the organohalogen compound which is added to carrier gas released from the heater can be prevented at an upstream region from the catalyst layer, in addition to realizing the effects claimed the first and fifth aspects of the invention, because the temperature of the carrier gas released from the heater is controlled to be higher than a temperature at which the organohalogen compound is destructed by the catalyst and lower than a temperature at which the organohalogen compound is destructed at least partially. Therefore, corrosion of the structural material at the upstream region from the catalyst layer can be prevented.
A practical example of the above advantages is explained hereinafter. When an organohalogen compound of low concentration is treated, the temperature of the carrier gas may be nearly the same as the temperature necessary for destructing the organohalogen compound with a catalyst layer. However, when an organohalogen compound of high concentration is treated, the temperature of the carrier gas before mixing with the organohalogen compound must be set higher than the temperature necessary for destructing Lithe organohalogen compound with a catalyst layer, because, the temperature of the carrier gas is decreased by mixing with the organohalogen compound. In the above case, the output power of the heater (for instance, the amount of the supplied fuel) is regulated so that the temperature of the carrier gas before being mixed with the organohalogen compound does not exceed the temperature for the partial destruction of the organohalogen compound, and the temperature of the carrier gas or a mixture of the carrier gas and steam is lower than the temperature for the partial destruction of the organohalogen compound and the temperature after being mixed with the organohalogen compound is higher than the temperature necessary for the destruction of the organohalogen compound by the catalyst layer. If the maximum usable temperature of the catalyst is lower than the temperature for the partial destruction of the organohalogen compound, the temperature must be regulated in a range lower than the maximum usable temperature of the catalyst layer.
In accordance with the seventh aspect of the invention corrosion by destructed gases generated by the destruction of the organohalogen compound with the catalyst layer can be prevented, in addition to realizing the advantages of claimed in the first and fifth aspects of the inventions, because the exhaust gas released from the catalyst layer is cooled down as soon as possible. When the organohalogen compound is destructed, strongly corrosive halogens and hydrogen halides such as chlorine, hydrogen chloride, fluorine, hydrogen fluoride, and the like corresponding to the kind of the organohalogen compound are generated at a high temperature. In order to resist against the above strongly corrosive gas of high temperature, heat resistant and corrosion resistant metals such as Ni. Nixe2x80x94Cr alloys, and the like, and heat resistant and corrosion resistant materials such ceramic coating, glass coating must be sued as structural materials of the apparatus. However, in accordance with the present invention, the corrosion environment at downstream region of the catalyst layer in the apparatus can be moderated by cooling down the exhaust gas released from the catalyst layer as soon as possible. For instance, if the temperature of the exhaust gas is decreased below 150xc2x0 C., fluorine resins other than the above inorganic materials can be used. If the temperature of the exhaust gas is decreased below 100xc2x0 C., vinyl chloride resins coated on the structural material can be used.
As a means for cooling the exhaust gas released from the catalyst layer, there are, for example, a method of installing a heat exchanger in the downstream region form the catalyst container, a method of cooling with washing liquid in a washer which is installed in the downstream region of the catalyst container, a method of cooling with bubbling in a liquid tank which is installed in the downstream region of the catalyst container, and a method of cooling with spraying in the downstream region of the catalyst container, etc. As a means for minimizing the range of strong corrosive environment and suppressing a head loss of the exhaust gas low, the method of cooling with spraying in the downstream region of the catalyst layer in the catalyst container is preferable. For the spraying liquid, a chemically stable liquid such as water is used. Further moderation of the corrosive environment can be realized by adding an alkali agent into the spraying liquid in order to neutralize partially the halogen and the hydrogen halide. As a dry process, a method for cooling by supplying cooled air into the exhaust gas at downstream region of the catalyst layer can be used.
In accordance with the eighth aspect of the invention generation of poisonous gas from the destructed gases which are generated by the destruction of the organohalogen compound can be prevented, in addition to achieving the advantages claimed in the first and fifth aspects of the invention, by cooling down the exhaust gas released from the catalyst layer as soon as possible because the organohalogen compound is a gas containing chlorine. For instance, the chlorine generated by the destruction of the organohalogen compound containing chlorine yields poisonous organochloro-compounds (dioxine and the like) by reacting with unburned components in the combustion gas after being maintained at a temperature approximately 300xc2x0 C. The generation of the poisonous organochloro-compound can be prevented by cooling down the exhaust gas released from the catalyst layer as soon as possible.
In accordance with the ninth aspect of the invention, a reactive material with acidic gases contained in the exhaust gas released from the catalyst layer is added into the exhaust gas released from the catalyst layer. Therefore, the acidic gas can be eliminated from the exhaust gas by reacting with the reactive material, in addition to achieving the advantages claimed in first and fifth aspects of the invention. Accordingly, the corrosive environment at downstream region of the catalyst layer can be improved. As the reactive material with the acidic gas, for instance, alkaline solution, slaked lime, and the like can be used. Even in a case using the alkaline solution, either of a method of spraying the alkaline solution into the exhaust gas and a method of bubbling the exhaust gas into the stored alkaline solution can be used. In accordance with the former method, a large surface area of the alkaline solution can be utilized, and accordingly, a large efficiency of the reaction with the acidic gas can be realized. Therefore, the facility for treating the exhaust gas can be made compact. In accordance with the latter method, the head loss of the exhaust gas system is increased, and a salt, which is a reaction product of the acidic gas and the alkali, is precipitated, grown, and adhered onto a wall of the structural material at a low temperature region. The adhered material has a possibility to choke the piping of the treating system. The former method does not have such a problem, because the alkaline solution always flows.
In accordance with the tenth aspect of the invention, mist does not enter into the catalyst layer, and therefore, corrosion of the structural material of the catalyst layer can be suppressed, in addition to achieving the advantage claimed in the seventh aspect of the invention, because a means for protecting the catalyst layer from entering the mist which is generated by the spraying the liquid from the means for spraying the liquid is provided. Practically, when the liquid is sprayed at downstream region of the catalyst layer in the catalyst container containing the catalyst layer, splash of the sprayed liquid enters into the catalyst layer, and causes a possibility to decrease the temperature of the catalyst, and to decrease the activity of the catalyst. In accordance with installing a means for protecting the catalyst layer from entering the mist, the above problem can be suppressed. The means for protecting the catalyst layer from entering the mist can be realized, for instance, by installing a baffle plate at an interval between the catalyst layer and the spraying space.
In accordance with the eleventh aspect of the invention, an amount of splash which migrates into the downstream region of the catalyst layer can be decreased, in addition to achieving the advantage claimed in the seventh aspect of the invention, because a means for preventing the mist, which is generated by the spraying the liquid from the means for spraying, from migrating into the downstream region is provided in a space at the downstream side exit of the catalyst layer. The above effect causes an advantage to improve an efficiency of eliminating acidic gas in the exhaust gas released from the catalyst layer. Practically, the splash of the sprayed liquid migrates into the piping which connects the chamber having the catalyst layer and an apparatus for treating the exhaust gas installed in the downstream region of the catalyst layer, and the migrated splash generates a new corrosion source by bringing humidity into the piping, inside of which must be naturally in a dried condition. The means for preventing the mist from migration can be realized, for instance, by providing a separating chamber, in which the gas velocity is slow, in the vessel containing the catalyst in order to settle down the mist in the air.
In a practical example of the present invention, the exhaust gas generated by the destruction of organohalogen compound is cooled down or neutralized partially in a vessel containing the catalyst, and subsequently, the halogen and the halogen compound are completely eliminated from the exhaust gas by an apparatus for treating the exhaust gas. A trace of undestructed organohalogen compound is contained in the exhaust gas released from the apparatus for treating the exhaust gas. However, the treated exhaust gas can be released without any further treatment or requires further re-treatment depending on the kind and the content of the undestructed component of the organohalogen compound.
If further treatment is necessary, the gas is adsorbed once by an adsorbent at the downstream region of the apparatus for treating the exhaust gas, and re-treating the gas which is re-generated and released from the adsorbent is generally performed. As the adsorbent, active carbon, zeolite, silica gel, active alumina, and the like are used. Practically, the treatment of the recovered and released organohalogen compound is performed continuously without stopping the destruction treatment of organohalogen compound by providing two systems of the adsorbing columns in parallel, recovering the one system while the other system is under operation, and introducing the recovered and released organohalogen compound into the catalyst under operation.
Steam can be heated by mixing with heated air, or by direct heating. However, if the organohalogen compound contacts with flame, a heating body, and a body at an elevated temperature higher than the destruction temperature of the organohalogen compound in the heater, the organohalogen compound destructs partially even if the heating temperature is below the destruction temperature, and the organohalogen compound has a possibility to generate corrosive materials as destruction products. Therefore, the direct heating by the heater is not desirable. In the above case, it is necessary to elevate the temperature of the steam to the necessary temperature for catalytic destruction by mixing the steam with previously heated carrier gas such as air, or a mixture of the carrier gas and steam.